US9121773B2ActiveUtilityA1
Gas sensors and methods of calibrating same
Est. expiryMar 13, 2033(~6.6 yrs left)· nominal 20-yr term from priority
Inventors:Alkis C. Makrides
G01N 25/18G01K 15/002G01K 15/005G01K 15/00
38
PatentIndex Score
0
Cited by
21
References
8
Claims
Abstract
A method is provided for calibrating a thermal conductivity sensor in a first medium A from measurements in a second medium B. The method includes maintaining the sensor at a substantially fixed temperature T 1 , and measuring a heat flux I B (T 1 ) from the thermal element in the second medium B. A corresponding heat flux I A (T 1 ) in the first medium A is calculated using known thermal conductivities of the first medium A and the second medium B.
Claims
exact text as granted — not AI-modifiedWhat is claimed is:
1. A method of calibrating a thermal conductivity sensor in a first medium A from measurements in a second medium B consisting of air free of any gaseous species of the medium A, the method comprising:
maintaining the sensor at a substantially fixed temperature T 1 ;
during the maintaining step, measuring a heat flux I B (T 1 ) in the second medium B;
calculating a corresponding heat flux I A (T 1 ) in the first medium A, from (i) the measured heat flux in the second medium B and (ii) known thermal conductivities of the first medium A and the second medium B; and
based on the calculation, calibrating the sensor for measurements of a mixture of medium A and medium B by relating measurements of the heat flux I B (T 1 ) to the corresponding heat flux I A (T 1 ), thereby facilitating measurement, using the sensor, of a concentration of medium A in the mixture based on a measured heat flux of the mixture, the heat flux I A (T 1 ), and the heat flux I B (T 1 ).
2. The method of claim 1 , wherein the first medium A comprises a member selected from the group consisting of methane, ethane, and propane.
3. The method of claim 1 , wherein the fixed temperature T 1 is in a range from about 70° C. to about 300° C.
4. The method of claim 1 , further comprising:
measuring a heat flux I M (T 1 ) of the thermal conductivity sensor in a mixture of a species S A and the second medium B, the species S A corresponding to the first medium A; and
calculating a concentration C A of the species S A in the mixture based on the heat flux I M (T 1 ), the heat flux I A (T 1 ), and the heat flux I B (T 1 ), according to
C
A
=
I
M
(
T
1
)
-
I
B
(
T
1
)
I
A
(
T
1
)
-
I
B
(
T
1
)
.
5. A thermal conductivity sensor for measuring a concentration C A of a species S A in a mixture of the species S A and a medium B consisting of air, the sensor comprising:
a thermal element; and
a processor configured to execute instructions stored in a non-transitory computer-readable medium to:
maintain the thermal element at a substantially fixed temperature T 1 ;
with the thermal element maintained at the substantially fixed temperature, measure a heat flux I B (T 1 ) from the thermal element in the medium B free of the species S A ; and
calculate a heat flux I A (T 1 ) from the thermal element in the species S A , the heat flux I A (T 1 ) corresponding to the fixed temperature T 1 of the thermal element, wherein the heat flux I A (T 1 ) is calculated based on the heat flux I B (T 1 ) and thermal conductivities of the species S A and the S A -free medium B at the fixed temperature T 1 to facilitate measurement, using the thermal element, of a concentration C A of the species S A in the mixture based on the heat flux I M (T 1 ), the heat flux I A (T 1 ), and the heat flux I B (T 1 ).
6. The sensor of claim 5 , wherein the species S A comprises a member selected from the group consisting of methane, ethane, and propane.
7. The sensor of claim 5 , wherein the fixed temperature T 1 is in a range from about 70° C. to about 300° C.
8. The sensor of claim 5 , wherein the processor is configured to execute instructions to:
measure a heat flux I M (T 1 ) from the thermal element sensor in a mixture of the species S A and the medium B; and
and calculate a concentration C A of the species S A in the mixture based on the heat flux I M (T 1 ), the heat flux I A (T 1 ), and the heat flux I B (T 1 ), according to
C
A
=
I
M
(
T
1
)
-
I
B
(
T
1
)
I
A
(
T
1
)
-
I
B
(
T
1
)
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